rtc: cros-ec: Fail suspend/resume if wake IRQ can't be configured

If we encounter a failure during suspend where this RTC was programmed
to wakeup the system from suspend, but that wakeup couldn't be
configured because the system didn't support wakeup interrupts, we'll
run into the following warning:

Unbalanced IRQ 166 wake disable
WARNING: CPU: 7 PID: 3071 at kernel/irq/manage.c:669 irq_set_irq_wake+0x108/0x278

This happens because the suspend process isn't aborted when the RTC
fails to configure the wakeup IRQ. Instead, we continue suspending the
system and then another suspend callback fails the suspend process and
"unwinds" the previously suspended drivers by calling their resume
callbacks. When we get back to resuming this RTC driver, we'll call
disable_irq_wake() on an IRQ that hasn't been configured for wake.

Let's just fail suspend/resume here if we can't configure the system to
wake and the user has chosen to wakeup with this device. This fixes this
warning and makes the code more robust in case there are systems out
there that can't wakeup from suspend on this line but the user has
chosen to do so.

Cc: Enric Balletbo i Serra <[e-mail]>
Cc: Evan Green <[e-mail]>
Cc: Benson Leung <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>
Acked-By: Benson Leung <[e-mail]>
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/rtc-cros-ec.c

···
 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 
 	if (device_may_wakeup(dev))
-		enable_irq_wake(cros_ec_rtc->cros_ec->irq);
+		return enable_irq_wake(cros_ec_rtc->cros_ec->irq);
 
 	return 0;
 }
···
 	struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);
 
 	if (device_may_wakeup(dev))
-		disable_irq_wake(cros_ec_rtc->cros_ec->irq);
+		return disable_irq_wake(cros_ec_rtc->cros_ec->irq);
 
 	return 0;
 }